title: Paradoxical response to exercise in asymptomatic hypertrophic cardiomyopathy: a new description of outflow tract obstruction dynamics.
abstract: OBJECTIVE
  The purpose of this study was to analyze left ventricular obstruction in patients with hypertrophic cardiomyopathy (HCM) during exercise echocardiography.
  
  
  BACKGROUND
  Despite the association of symptoms with left ventricular outflow tract obstruction in HCM, there exist paradoxical situations in which significant intraventricular gradients (>50 mm Hg) at rest occur in conjunction with excellent exercise tolerance.
  
  
  METHODS
  To examine this phenomenon, we performed exercise echocardiography and analyzed the clinical status of 107 HCM patients with and without resting obstruction.
  
  
  RESULTS
  At rest, 69 patients had no obstruction and 38 exhibited an intraventricular gradient, 9 of whom exhibited a decrease in gradient of at least 30 mm Hg (99.4 ± 35.5 mm Hg to 30.2 ± 14.3 mm Hg, p < 0.001) during exercise (paradoxical response to exercise [PRE]). The PRE patients presented with a significantly lower New York Heart Association clinical class and higher left ventricular volumes and arterial pressure both at rest and during exercise than HCM patients in whom the gradient increased or did not change during stress echocardiography. Finally, PRE patients exhibited a trend toward a reduced rate of cardiac events.
  
  
  CONCLUSIONS
  Our study reports a subgroup of HCM patients, designated PRE based on a decreased intraventricular gradient during exercise. The reduced exertional obstruction may account for the better functional class and trend toward fewer clinical events in PRE patients.
authors.affiliation: University of Bordeaux, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Lafitte
authors.forename: Patricia
authors.initials: P
authors.lastname: Reant
authors.forename: Cecile
authors.initials: C
authors.lastname: Touche
authors.forename: Xavier
authors.initials: X
authors.lastname: Pillois
authors.forename: Marina
authors.initials: M
authors.lastname: Dijos
authors.forename: Florence
authors.initials: F
authors.lastname: Arsac
authors.forename: Jerome
authors.initials: J
authors.lastname: Peyrou
authors.forename: Michel
authors.initials: M
authors.lastname: Montaudon
authors.forename: Philippe
authors.initials: P
authors.lastname: Ritter
authors.forename: Raymond
authors.initials: R
authors.lastname: Roudaut
authors.forename: Anthony
authors.initials: A
authors.lastname: Demaria
mesh_terms: D000328:Adult; D000368:Aged; D058070:Asymptomatic Diseases; D001794:Blood Pressure; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015331:Cohort Studies; D025401:Echocardiography, Stress; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012146:Rest; D012189:Retrospective Studies; D014694:Ventricular Outflow Obstruction / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*
keywords: HCM; LV; LVOT; LVOTO; NOB; NYHA; New York Heart Association; OB; OBI; PRE; SAM; exercise echocardiography; hypertrophic cardiomyopathy; left ventricular; left ventricular obstruction; left ventricular outflow tract; left ventricular outflow tract obstruction; nonobstructive hypertrophic cardiomyopathy at rest; obstructive hypertrophic cardiomyopathy at rest; obstructive hypertrophic cardiomyopathy at rest with increased gradient or no change during exercise; paradoxical response to exercise; systolic anterior motion